Broad band antenna



June 7, 1949.

W- W. HANSEN BROAD BAND ANTENNA Filed Sept. 20, 1943 INVENTO W/u MM//,4/vs/v 3 4 mm ATTORNEY Patented June 7, 1949 BROAD BAND ANTENNAWilliam W. Hansen, Garden .City, N. Y. .assignor Delaware to'The SperryCorporation; a corporation of Application September 20, 1943, SerialNo..503.;Q6.6

2 Claims. 1

My invention relates to antennae or radiators for radio communicationand signaling systems, and concerns particularly radiators suitable foruse in high frequency radio systems such as may be used in connectionwith object detection.

An object of my invention is to provide an antenna having a pattern likea dipole, but having a broader frequency hand. For example, an object isto provide an antenna having a radiation resistance at least sixteentimes that of the conventional dipole and having a value of Q (orquality factor) onefourth that of a dipole in order to broaden thefrequency band.

A further object of my invention is to provide an antenna which may beburied in a dielectric sphere.

A further object of my invention is to provide a. double-ended antennawhich is useful in pulse systems and in which sparking is prevented.

Still another object of my invention is to pro.- vide an antenna arrayhaving a broad band but with a pattern similar to an end fire or a broadside array of dipoles.

Other and further objects and advantages will become apparent as thedescription proceeds.

In carrying out my invention in its preferred form, I utilize a rod orWire of suitable conducting material which is electrically continuousfrom one input terminal to the other and which may be bent to lie alonga plurality of planes, .at least four in number, including a pair ofparallel planes, which are substantially perpendicular to a second pairof parallel planes.

A better understanding of the invention will be afforded by thefollowing detailed description considered in connection with theaccompanying drawings, in which:

Fig. 1 is a perspective view .of one embodiment of my inventioncomprising a substantially rectangular form of antenna;

Fig. .2 is a perspective view of a modification in the arrangement ofFig. 1 in which the .3 -tenna conductor is bent in the form of circularsegments or smooth curves instead of rectangles or straight-sidedfigures;

Fig. ,3 is aschematic diagram illustrating the arrangement-of theantennaon the surfaceof a sphere utilizing wire consisting of circularsegme s;

Fig. 4 is .a view .of a surface development of the antenna of Fig. 3;

Fig. 5 is a perspective view of .a modification of the arrangement ofFig. ,1 for producing the effect of a plurality of dipoles in broadsidearray;

Fig, 6 is-a crossesectionalviewof the arrangement of Fig. ;5 and adiagram of the radiation pattern; and

Fig. ,7 is a perspective view of the antenna shown in Fig. 1.

Lik reference characters are utilized throughout the drawings .todesignate like parts.

In the embodiment of Fig. 1 an antenna is formed by bending a unitarylength of wire 13 along the lateral edges of a square base prism (shownby dotted lines in Fig. 7) with input connections at the center ,of oneof the edges of the prism. Preferably the corners are rounded to avoiddiscontinuity-efiects. Input terminals from a suitable transmission line(not shown) are represented by the ends H and -l;2 of the length of Wirel3 forming the antenna. The portions of the wire at the terminals H andI2 are bent at right angles in opposite directions to form two segments1:4 and I5, which define one lateral edge of a square prism. The upperend of the wire segment 14 is bent to be tangent to one of the top edges16 of the square prism or to actually form the .edge of the prism andthis portion of the wire is bent again to form a second lateral edge Hof thesquare base prism adjacent a segment of wire 18 forming one of thelower edges of the Square base prism or tangent thereto. A furthercontinuation of the wire 19 forms a third lateral edge of the squareprism. Parallel to the segment of wire 16 is a continuation 21 .of theportion IS. The portion -2l forms or is tangent to the second top edgeof the square prism and together with the portion 16 defines the topofsuch a prism. The antenna is completed by a portion .22, forming thefourth lateral edge of the square prism and a portion 23 formingflortangent to a second bottom edge of the square prism.

It will be observed that the portions of the wire l4, l5, l6, and .H liein one plane and the portions l9, 2] and Z'Z'lie in a second planeparallel .to the first; and that likewise portions 11, ,l 8 and .19 liein a plane which is perpendicular to the first two planes and parallelto a second plane defined by the portions 14, i5, 22 and '23 of theantenna. Thus, it will .be observed that this embodiment .of theinvention consists of a length .of conductor bent into four planes, twoof 'which are parallel to each other and perpendicular to the lattertwo, which are parallel to each other. v

The portions of the wire are thus bent to in- ,clude straight portionsthat define. two parallel planes, but if preferred these portions may becurred or s irc la in qrrn. a l us ra d i 3 Fig, 2. With thisarrangement, any three consecutive portions of the wire I3 form aU-shaped plane figure.

In order to obtain the desired radiation characteristics, each of thelengths of the longitudinal portions l1, I9, 22 and I l-H together withone-half their respective end portions I6, I 8, 2| and 23 are of theorder of a half-wave length of the wave which is intended to bepropagated or detected by the antenna (e. g. length l9+ end I8+ end 2|is approximately equal to a half wave length). The spacings of theseportions of the antenna, or the lengths of the portions i8, 23, I6 and2|, are so chosen as to leave the currents flowing in the portions [1,I9, 22, I4 and I5 substantially in phase if dipole radiationcharacteristics are desired. The cross-connections I6, 2|, I8, 23 arerelatively short and the longitudinal portion-s are substantiallyonehalf an electrical wave length, making due allowance for the effectof the cross connections. Standing current waves in all of thelongitudinal portions of the Wire will produce field components whichadd in phase.

With these portions of the wire equal a half wave length, it will beapparent that the U- shaped portion formed by segments l4, I6 and halfof segment I! may be considered equivalent to a half wave length. Alsohalf of segment 11, all of i8 and half of IS form a U-shaped member thatmay be a half wave length. It will further be apparent that these.U-shaped members define planes (Fig. 7) that are perpendicular, and twosimilar U-shaped portions define additional sides of the prisms tocomplete the antenna.

As already suggested, the end portions it, 2!, i8, 23 may be curved orstraight, as desired. Furthermore, the entire radiating portion of theantenna, excluding the lead-in portions I I and I2 from the terminals IIand [2, may be curved as illustrated in Fig. 2. The use of circularsegments of wire facilitates the adaptation of the antenna to aspherical outline. For example, as illustrated in Fig. 3, if the wire I3is bent into four successive semicircles 24, 25, 26, 21, and thesesemicircles are arranged with their diameters along the sides of asquare and lie in planes forming a cube having its sides perpendicularto the square (as shown by dotted lines in Fig. 2), the semicircles willthen lie in small circles of a sphere 23, thus lying in the sphericalsurface. The fact that the antenna of Fig. 3 is composed of semicirclesis illustrated by the development shown in Fig. 4, where the semicircles24 and 26 are laid out in true form on the development plane and thesemi-circles 25 and 21 have been straightened out by flattening thecurve defined by the semicircles 25 and 21 of Fig. 3 into thedevelopment plane, 1. e., the plane of the paper. It will be seen fromFig. 4 that the diameters 24' and 26 of the semicircles 24 and 26 arecontiguous to the semicircles 25 and 21. Thus the diameters 24' and 23'form a square with the diameters 25' and 21' as shown in Fig. 3. Each ofthe semicircles is effectively one-half electrical wave in length forthe desired radiation characteristics.

Fig. 3 illustrates also the manner of connecting the antenna to acoaxial transmission line comprising an outer cylinder 30 and a coaxialinner conductor 29. The terminal I 2, for example, may be connected tothe internal conductor 29 and the terminal ll may be connected to thesheath or cylinder 30.

If desired, the antenna of Fig. 3 may merely be formed on a sphere suchas shown at 28, or it may actually be mounted in semicircular grooves onthe surface of a sphere 28 composed of suitable dielectric material,such as either polystyrene or polymerized methyl methacrylate (Lucite)The whole may then be encased by a further coating of a similardielectric material to form a. spherical radiator.

The antenna illustrated is especially useful for pulse systems such asthose used in object detectors and target locators, for example. Thepossibility of imbedding the antenna in dielectric material makes itpossible to prevent sparking.

It will be understood that when the antenna is to be imbedded in thedielectric substance all of its physical dimensions should be reduced inthe ratio of 1: Vi, where E is the electric inductive capacity of thesubstance compared with air.

Both the rectangular and curved forms of antenna illustrated in Figs. 1to 3 will be observed to have four folds, represented in Fig. l by l8,it, 2!, 23, and in Fig. 3 by the semicircles 24, 25, 2'5, 2?.

The radiation resistance and consequently the radiant power for constantcurrent is increased in the ratio of the square of the number of folds,whereas the energy stored increases only with the number of folds. The Q(or quality factor) of elements of a radio system is expressed by theratio of the stored energy to the dissipated energy in the element andaccordingly the Q of the an-- tenna is inversely proportional to thenumber of folds. Thus, in the four-fold arrangement of Figs. 1 to 3, theQ is made one-fourth that of the dipole and the frequency band of theantenna is correspondingly broader than that of a dipole.

If the radiation pattern of a broadside array of dipoles is desired, itmay be obtained by arranging the folds in such a manner that there is agreater number of folds in one pair of planes than in another pair ofperpendicular planes. For example, as illustrated in Fig. 5, an antennawith twelve folds may be constructed with a single length of conductorbent along the four side surfaces of an oblong base prism (shown bydotted lines in Fig. 5). In this case, two of the folds 3! and 32 andadjacent portions of wire define two parallel end planes and theremaining folds with their adjacent portions of wire define two otherparallel planes which serve as side planes and are perpendicular to theend planes. The cross-sectional view of Fig. 6 represents therelationship between the successive conductors and shows the radiationpattern 33, 34 which may be obtained with the longitudinal spacingbetween conductors equal to M4. The lateral spacing between conductors,that is, the length of each of the folds 3|, 32, is preferably of theorder of M4 or less to minimize radiation effects from the folds 3i and32.

I have herein shown and particularly described certain embodiments of myinvention and certain methods of operation embraced therein for thepurpose of explaining its principle of operation and showing itsapplication, but it will be obvious to those skilled in the art thatmany modifications and variations are possible, and I aim, therefore, tocover all such modifications and variations as fall within the scope ofmy invention which is defined in the appended claims.

What is claimed is:

l. A radio antenna comprising a single unbroken length of wire forming asubstantially U-shaped structure, said structure comprising a pluralityof substantially semi-circular portions lying in spaced parallel planesand discretely faced to each other, and other semi-circular portionsconnecting the free ends of said first-mentioned semi-circular portionsand lying in spaced parallel planes, which planes are perpendicular tosaid first mentioned planes, and the ends of said length of wire havingelectromagnetic energy fed thereto.

2. A radio antenna comprising a single unbroken length of wire forming asubstantially U-shaped structure, said structure comprising a pluralityof substantially semi-circular portions lying in spaced parallel planesand discretely faced to each other, and other semi-circular portionsconnecting the free ends of said first mentioned semi-circular portionsand lying in spaced parallel planes, which planes are perpendicular tosaid first mentioned planes, the ends of said length of wire havingelectromagnetic energy fed thereto, and dielectric means having adielectric constant different from air substantially surrounding saidantenna.

W. HANSEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

5 UNITED STATES PATENTS Number Name Date 1,555,345 Willoughby Sept. 29,1925 1,981,780 Latour Jan. 15, 1935 1,999,258. Roberts Apr. 30, 19352,053,658 Franklin Sept. 3, 1936 2,153,589 Peterson Apr. 11, 19392,273,955 Grimditch Feb. 24, 1942 2,283,914 Carter May 26, 19422,316,623. Roberts Apr. 13, 1943 15 2,373,206 Thomas Apr. 10, 19452,380,333 Scheldorf July 10, 1945 2,383,857 Hardy et al. Aug. 28, 1945FOREIGN PATENTS 20 Number Country Date 709,543 I France Aug. '1, 1931801,595 France May 23, 1936

